Different sulfides were oxidized to the corresponding sulfoxides, which is useful in drug industriesand important in biological activities, with a novel magnetically separable catalyst consisting oftungstic acid supported on silica coated magnetic nanoparticles in water as a green solvent in a goodto excellent yield without any over oxidation to sulfones in a simple, selective, and eco-friendlyway. The catalyst can be separated from reaction condition using an external magnetic field andreused for several times as its first structure. Using some different microscopic and spectroscopictechniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM),Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and EDXspectroscopy.